Breast Cancer and Diet: Not Just What, But When

My onetime patient and student, Nicole Larizza, earned her MS degree in nutrition studying the effects of nutrition in childhood on breast cancer risk in adulthood. Her important insights have led her to establish an organization dedicated to the early prevention of breast cancer, Nourish Our Girls.

I found the information Nicole shared with me important and provocative -- and felt it deserved to be shared. My questions and her answers follow to that end.

As women, we tend not to think about breast cancer until mid-life -- our 40s, 50s, and beyond -- when our friends, sisters, mothers, or coworkers are diagnosed with this dreaded disease. But adult breast health is largely determined much earlier in life, when the breast tissue is developing. During this time, the breast is most vulnerable and sensitive to nutritional and environmental stimuli. Research shows us that consumption of certain foods during the breast development process may actually change the physiology of the breast, thereby making it more or less susceptible to future cancer. One example of this is soy foods. Regular consumption of whole, traditional forms of soy during puberty is associated with the growth of fewer terminal ductal-lobular units (TDLUs) in the breast. These TDLUs are the end point of each mammary duct that extends out from the nipple, and are the site where the overwhelming majority of breast cancers originate. If we reduce the number of TDLUs in the fully-developed breast by altering a girl's pubertal diet, then we reduce the opportunity for cancer to occur there. This is just one of many examples about how diet during the breast development stage may affect physiology and influence risk as a result.

2. How does a girl's nutrition during childhood and adolescence affect her risk of breast cancer later in life?

The development of cancer is a multi-step process at the cellular level. Very simply, it begins with initiation when a single cell is damaged. This is followed by promotion as the damaged cell replicates and makes more damaged cells, and finally culminates with progression as masses of damaged cells spread throughout the body, infiltrate other tissues, and affect function. This process may take up to 35 years. With women being diagnosed at earlier ages now -- in their 40s, 30s, and even some in their 20s -- think about when that disease process may have started! The food a young girl eats may directly affect her risk of breast cancer by intervening at the earliest points along the cancer continuum. The presence of antioxidants and other nutrients may protect cells from becoming damaged in the first place, and may slow down or prevent the promotion of cell damage thereafter. Conversely, toxins and anti-nutrients like sugar and synthetic fats may actually cause cell damage or create a cellular environment in which cancer grows and thrives.

More indirectly, but just as important, certain dietary patterns and food intakes during childhood and adolescence are associated with the timing of menarche. Earlier menarche is an independent risk factor for adult breast cancer because it extends the window of exposure to estrogen. Estrogen has been implicated as a stimulus for cell division as well as a promoter of hormone-receptive breast tumors. As such, women with a higher lifetime exposure to estrogen have higher rates of breast cancer. Any behaviors we can modify to delay that first period, and shorten the window of estrogen exposure, may therefore result in decreased cancer risk. These behaviors include eating a lower-fat, lower-protein, higher-fiber diet, as well as being physically active and maintaining a lean body weight.

3. Which foods or dietary patterns during childhood/adolescence help to reduce risk of adult breast cancer?

Based upon available clinical evidence, there are essentially five dietary patterns that appear to be protective. The mechanisms of action are yet to be completely elucidated, but these patterns are associated with reduced risk of adult breast cancer and other breast cancer biomarkers. First, girls should aim to get more of their dietary fat from plant sources like nuts, seeds, avocado, and vegetable oils, and from cold-water fish like salmon, tuna, and halibut. They should limit dietary fat from meats, cheese, and dairy products. Second, girls should also try to get more of their protein from plant-based sources like legumes as opposed to relying on meat, poultry, eggs, and dairy products as their primary sources. Third, they should eat cruciferous vegetables such as broccoli, cabbages, kale, cauliflower, and Brussels sprouts at least a few times per week, ideally raw or lightly cooked to preserve their nutrients. These powerhouse vegetables contain cancer-fighting glucosinolate compounds that protect cells from initial damage and deter the proliferation of any further cell damage. Fourth, girls should also make whole, traditional soy foods like tofu, tempeh, and miso a regular part of their weekly menus. Similar to the broccoli family, these foods contain various compounds -- indoles and isothiocyanates, in this case -- that protect cells from damage and stimulate genes that suppress tumor formation. Lastly, girls should endeavor to eat a high-fiber diet, consisting of plentiful beans, lentils, nuts, seeds, fibrous vegetables and fruits, and unprocessed whole grains. Dietary fiber may help to decrease her exposure to high levels of estrogen, which in turn reduces her risk of breast cancer later in life.

4. Are there any foods that may increase risk and should therefore be avoided by young girls?

Especially for young girls, we should keep our focus on the positive -- getting more of the good, health-supportive foods into her diet -- rather than on the negative. If we persevere in our efforts, these nutrient-dense foods will ultimately crowd out some of the empty, nutrient-poor choices without creating an air of deprivation or food restriction. That said, there are, without question, certain dietary habits during childhood and adolescence that are associated with higher breast cancer risk later in life. High sugar intake, or a high-glycemic diet pattern, high animal protein consumption, low fiber intake, and any amount of alcohol consumption are all related to higher risk and should be avoided. Practically, girls need to learn to view sugary treats as just that -- treats that are consumed occasionally rather than every day, or after every meal. They should be exposed to the endless possibilities for "meatless meals" and recognize that lunches and dinners don't need to be centered around animal protein. Vegetables and legumes shouldn't just be a side dish to their meal -- they should be the meal! Girls should avoid refined and highly-processed grains like white breads, bagels, cereals, crackers, baked goods, and pastas. Instead, they should choose unrefined, minimally-processed whole grains and lots of vegetables and fruit in every meal to make sure they get enough fiber.

5. How can families apply this knowledge to their daughter's or granddaughter's diet in order to reduce her risk?

There are some really easy ways to change our girls' eating habits to reduce their breast cancer risk. Instead of butter, dress vegetables with extra-virgin olive oil. Instead of cream cheese on a bagel, serve natural peanut butter or almond butter on a whole-grain bagel. Replace the cheese on her sandwich with sliced avocado or a smear of flavored hummus. Make a few dinners each week "meatless meals" that are centered around beans, lentils, other legumes, and vegetables. Forget the ground beef and make vegetarian chili loaded with kidney beans, vegetables, and spices. Send broccoli or cauliflower florets with hummus as a snack in her lunchbox. Switch her pasta from traditional white pasta to a whole-grain or multi-grain blend that is higher in fiber. Throw away those packets of sugary instant oatmeal and make your own using old-fashioned or steel-cut oats, and flavor it with fruit, nuts/seeds, and a drizzle of maple syrup. Ditch the white rice and experiment with higher-fiber grains like wheatberries, farro, quinoa, barley, and wild rice instead. Throw a handful of kale leaves into her smoothie for great green color and dose of cruciferous vegetable at the same time. The possibilities are endless, and the health impact is immeasurable!

6. What is the take away message for anyone who has girls in their life who may be going through breast development?

Think of it this way: The breast is like a tree that grows from a seedling. If the seedling is exposed to health supportive nutrients, it is much more likely to develop a strong root system and grow into a mature tree that is able to withstand the storms mother nature may send its way. If that same seedling were starved of nutrients and exposed to toxins or anti-nutrients instead, it may still eventually grow into a full-sized tree. But without the foundation of a robust and healthy root system, that tree will likely be weaker and more susceptible to broken branches or uprooting when storms hit. Breast cancer is a very big, very complex storm. Admittedly, it cannot be eradicated through diet alone, regardless of when or how we structure it. But the evidence is compelling that nutrition during the breast development stage can influence the long-term health of this critical organ. Quite simply, we need to nurture our girls' seedlings the best we can now... so they will grow to be strong, mature, healthy breasts for a lifetime.

-fin

Nicole Larizza, MS is the Founder and Chief Nutrition Officer of Nourish Our Girls, an educational campaign to raise awareness about the role of childhood and adolescent diet in breast cancer risk reduction. She holds a Masters of Science in Human Nutrition from the University of Bridgeport. To learn more, contact her at nicole@nourishourgirls.org or visit www.nourishourgirls.org.